San Francisco 49ers starting quarterback Nick Mullens (4) looks to pass against the Oakland Raiders in the first quarter of their NFL game at Levi’s Stadium in Santa Clara, Calif., on Thursday, Nov. 1, 2018. (Jose Carlos Fajardo/Bay Area News Group)

Nick Mullens looked like a proven starter in his NFL debut. (Randy Vazquez/Bay Area News Group)

San Francisco 49ers starting quarterback Nick Mullens (4) before calling a play versus the Oakland Raiders in the fourth quarter of their game at Levi’s Stadium in Santa Clara, Calif., on Thursday, Nov. 1, 2018. (Randy Vazquez/Bay Area News Group)

San Francisco 49ers starting quarterback Nick Mullens (4) walks off the field after leading his team to a 34-3 win over the Oakland Raiders at Levi’s Stadium in Santa Clara, Calif., on Thursday, Nov. 1, 2018. (Randy Vazquez/Bay Area News Group)

San Francisco 49ers starting quarterback Nick Mullens (4) after leading his team to a 34-3 win over the Oakland Raiders at Levi’s Stadium in Santa Clara, Calif., on Thursday, Nov. 1, 2018. (Randy Vazquez/Bay Area News Group)

San Francisco 49ers starting quarterback Nick Mullens (4), center throws a pass agains the Oakland Raiders in the first quarter of their game at Levi’s Stadium in Santa Clara, Calif., on Thursday, Nov. 1, 2018. (Randy Vazquez/Bay Area News Group)

But check back next week, likely on Thursday when Shanahan next meets the media.

With players given four days off after a 34-3 rout of the Raiders, Shanahan is reluctant to announce that Mullens will get an encore start Nov. 12, when they host the New York Giants on ESPN’s “Monday Night Football.”

“I don’t need to decide it yet,” Shanahan said Friday about the QB call. “I’ll take my time with it, and with all the guys out of the building, I’d like the full team here when I decide that.”

SANTA CLARA, CA – NOVEMBER 1: San Francisco 49ers’ Pierre Garcon (15) hands the ball to San Francisco 49ers starting quarterback Nick Mullens (4) after Mullens through a touchdown against the Oakland Raiders in the first quarter at Levi’s Stadium in Santa Clara, Calif., on Thursday, Nov. 1, 2018. (Nhat V. Meyer/Bay Area News Group)

Reading between the lines, Shanahan is simply being respectful to his other option, C.J. Beathard, who went 0-5 upon replacing the injured Jimmy Garoppolo. Beathard’s wrist and thumb injuries in Sunday’s loss at Arizona further prompted Thursday’s switch to Mullens, who passed for 262 yards and three touchdowns with no interceptions or sacks.

The 49ers (2-7) will reconvene Tuesday to begin preparations for the Giants, who take a 1-7 record and five-game losing streak into this weekend’s bye.

Mullens’ former spot as the third-string QB was filled again by Tom Savage, who signed on Friday for the third time in as many weeks.

More tidbits on Mullens:

— Why wasn’t he drafted last year? Aside from teams not envisioning him as a Nos. 1 or 2 option, Mullens’ frame (6-foot-1, 210 yards) and Southern Miss’ spread offense weren’t wooing teams, as the 49ers were the only team to host him on a pre-draft visit.

Said Shanahan: “Nick’s not the tallest guy, not the biggest guy. … He played in a spread offense, though, so you weren’t seeing him under center and it was hard to envision how he would be. But the type of guy he was, the way he did within his offense, we knew he was a good football player.”

— On Mullens’ preparation method of listening to simulated crowd noise in headphones and barking out play calls: “I didn’t know about the crowd noise but it doesn’t surprise me at all. That’s the type of guy he is, that’s what I mean when I said he’s a machine. He’s always working.”

— On teammates’ respect: Unanimous praise of Mullens in the locker room will factor into Shanahan’s evaluation. But, he noted: “All of our quarterbacks have a lot of respect on our team, starting with Jimmy, going to C.J. and then to Nick. All our guys work pretty hard and are pretty tough guys.”

MOSTERT DONE: Raheem Mostert’s breakout season is over, the result of a forearm fracture that required surgery Friday but should have him healed for 2019. Mostert proved this season he’s more than a special-teams asset. He averaged a team-best 7.7 yards per carry (34 carries, 261 yards).

With Matt Breida and Alfred Morris capable as a top tandem, the 49ers’ third rusher could come from their practice squad in Jeff Wilson or Matt Dayes, although Shanahan said they may work out free agents in the next week, too. Mostert also will be missed on special teams, although rookie Tarvarius Moore has shined there, too.

Said Shanahan: “For the two years we’ve been here, Raheem’s been one of the better special teams players in the league. What he’s done for us on offense these last few weeks has been huge. He got his opportunity with some injuries, and faced adversity right away with the turnover. He completely bounced back and made himself a heck of a back.”

DRAFT STEAL: George Kittle (41 catches, 692 yards) ramped up his pace to become the first 49ers tight end to eclipse the 1,000-yard mark. Not bad for last year’s 146th overall selection, a fifth-round steal who the 49ers figured would go in the third.

Said Shanahan: “To me, he looks like a first-round talent, but we had a feeling he was going to fall, because he didn’t do a lot in the passing game. We always heard people talking about him as a run blocker, which is one reason we really liked him.

“But the main reason was the pass game. He didn’t get to show that a ton. That helped him not get noticed the first couple rounds, but we were very surprised he fell to the fifth.”

McGLINCHEY’S BLOCK: Leading Mostert down the sideline 50 yards down field was right tackle Mike McGlinchey, whose final block inside the 5 indeed sprang Mostert for his first career touchdown. Is that how Shanahan drew it up?

“No. He wanted to get on TV longer. He should have thrown early in the play and taken guys legs out on the edge,” Shanahan quipped. “I think the O-line gave him a show-off fine for trying to be on TV so long down the field. No, I’m just joking. He did a heck of a job. It was awesome.”

WATSON’S DEBUT: Typecast as special-teams ace, outside linebacker Dekoda Watson came off injured reserve (hamstring) and looked like an elite pass rusher (1 1/2 sacks, 3 quarterback hits). “He probably has our best speed off the edge, just coming off the ball fast, and he can turn to power very quickly,” Shanahan said. “Having that speed and bull rush, it condenses the pocket, and it got him som production but also helps others.”